1. Field of the Invention
The present invention relates generally to an apparatus and a method for changing a network attach mode in a mobile communication terminal, and more particularly, to an apparatus and a method for changing a network attach mode in a mobile communication terminal using a Global System for Mobile (GSM) scheme and a General Packet Radio Service (GPRS) scheme.
2. Description of the Related Art
A mobile terminal using GSM and GPRS is required to perform a GPRS attach procedure to register itself in a Serving GPRS Support Node (SGSN), which is a member of a GPRS network. In the GPRS attach procedure, the mobile terminal transmits a registered network position, identification (ID), and security information to the SGSN, and then the SGSN accepts the attach attempt of the mobile terminal through a user authentication process and makes the mobile terminal ready for the GPRS.
Network providers define an auto attach mode and a manual attach mode according to a point of time where the mobile terminal is connected to the GPRS.
In the auto attach mode, the mobile terminal performs the GPRS attach procedure when power is turned on, and maintains the GPRS attach state such that a user can use the GPRS at any time. Additionally, the mobile terminal in the manual attach mode performs the GPRS attach mode when a GPRS-related service (e.g., Wireless Application Protocol (WAP), Multimedia Message Service (MMS), etc.) is executed, and terminates the GPRS attach mode when the executed GPRS-related service is terminated.
In the auto attach mode, because of constantly maintaining the GPRS attach state, a user can instantly use the GPRS as soon as the GPRS related service is requested. Contrarily, in the manual attach mode, the GPRS attach procedure is performed only when a user requests the GPRS-related service. Therefore, it takes time for the mobile terminal to connect to the GPRS. Since the user notices the delay in the manual attach mode, conventional network providers usually set the auto attach mode as a default mode.
When trying to connect with the GPRS, a GPRS attach method can be different according to an interface between a Mobile Switching Center (MSC) and a SGSN in a network of the mobile terminal. When there is no interface between the MSC and the SGSN, the mobile terminal tries to connect with the GSM and the GPRS separately. When there is an interface between the MSC and the SGSN, the mobile terminal tries to connect with the GSM and the GPRS simultaneously.
When the GPRS attach procedure fails in the auto attach mode, the mobile terminal reattempts the GPRS attach procedure periodically until the GPRS attach state is successful. At this point, in case that the mobile terminal is connected to the GSM and the GPRS separately, only the GSM is in use. In case that the mobile terminal is connected the GSM and the GPRS simultaneously, neither the GSM nor the GPRS cannot be in use. The GPRS attach failures can occur due to an interface problem of the MSC or the SGSN, an internal problem of the SGSN, and database.
On the other hand, when the GPRS attach procedure is successful in the auto attach mode, the mobile terminal continuously maintains a GPRS attach state even though the GPRS is not in use. That is, when each time a Routing Area (RA) is changed, the GPRS attach state is maintained in order to update the RA.
As described above, when the GPRS attach procedure is successful in the mobile terminal according to a conventional art, the mobile terminal maintains the GPRS attach state even if the GPRS is not in use. Therefore, network resources are wasted. Moreover, when the GPRS attach procedure fails, the mobile terminal reattempts the GPRS attach procedure until the GPRS attach procedure is successful. Therefore, the network load increases. In particular, when the GPRS attach procedure fails due to uncertain network problems, the increased network load can cause additional problems in the network.